Information processing systems in which a plurality of information processing apparatuses, each of which has a central processing unit (CPU) and a memory, are combined have recently been used. Such an information processing system connects between the information processing apparatuses with a crossbar (XB), thereby enabling communication between the CPUs of different information processing apparatuses.
When the crossbar fails, communication between the information processing apparatuses becomes impossible, and the failure of the crossbar affects the entire information processing system. Given this situation, crossbar diagnosis is important in order to increase the reliability of the information processing system.
Given these circumstances, there is a crossbar diagnosing technique that locates a trouble by sending, for a crossbar switch under instructions from a CPU, a test pattern from a node as a data transfer source to another node in data transfer in which a trouble occurs.
There is a conventional technology that, when a trouble occurs in a switch, prevents a system failure by controlling so as to perform inter-node data transfer via a crossbar switch other than an inter-node crossbar switch including the switch in which the trouble occurs. Conventional technologies are disclosed in Japanese Laid-open Patent Publication No. 2000-242520 and Japanese Laid-open Patent Publication No. 2006-39897, for example.
However, the crossbar diagnosis technique under instructions from a CPU has the problem that, when the CPU is being used by an information processing system, diagnosis is not performed, unless the operation of the information processing system is stopped.